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XML, Menus, and PHP The menu you see on the left is dynamically driven from an XML File using PHP. <em>(that menu is no longer there but go with it anyway -<strong>ED</strong>)</em> Why, you ask? What would possess me to do such a thing? Very simple, I didn't want to pay for a DB server on the host. Also I wanted it to be dynamically driven. The answer? A text file. But how to easily get information out of the text file and onto the page? Again an answer presents itself....<br /> <ol> <li>XML: A way to store and parse data in text files <p>I was going to use XML to store my Data. It offered the following benefits: It was a text file, and it had a number of ready to use parsers in all the common Server Scripting platforms. I could use the file anywhere. The first step, of course, was to decide on the XML elements to use and how they would be used in the document. I had to write an XML spec of sorts so I knew how to interpret the file.</p> <ol> <li><p>First, I needed a Root element. XML documents require a document root element in order to be valid. We'll call that element the "map" element. After all, this document is going to amount to a sitemap of sorts. Which brings us to a side benefit of using XML. I can use the same file to generate a dynamic sitemap should I wish to and so can anyone else. I can provide this document publicly and anyone can host a way to get anywhere on my site from theirs. Who knows? It may be useful some day. Right now, our document looks like this:</p> <pre><code>< ?xml version='1.0' ?>; <map> </map></code> </pre></li> <li><p>Next, we need to have an element that holds all the data about one link. We'll call that the "section" element since it describes a section of the site. We also need elements inside this element to hold all the pieces we need to know to build our menu. In this case we are storing the link, the description, and the name of each link for the menu. Those elements are:</p> <ol> <li>link</li> <li>description</li> <li>name</li> </ol> So now our document looks like this: <pre><code>< ?xml version='1.0' ?> <map> <section> <link> </link> <description> </description> <name> </name> </section> </map></code></pre></li> <li><p>Each section element can be repeated as many times as necessary. The section element can only hold one link, description, and name element. That concludes our specs for the XML document.</p></li> </ol></li> <li>The Parser. <p>Now I had to select a parser to use, my platform for development at the time happened to be PHP. So what did PHP offer in the way of XML parsers? PHP actually had two parsers available to use. One was a SAX parser and the other is a DOM parser. At the time of this project, however, only the SAX Parser was included in the default distribution of PHP. So Sax it was.</p> <p>SAX parsers are event driven parsers. They are simpler to learn but harder to implement than DOM parsers. Event driven parsers work by firing events when something happens as it goes through the text line by line. The events that fire are:</p> <ol> <li>element start</li> <li>element end</li> <li>cdata</li> </ol> <p>So, you write handlers for each element and the parser calls them as each event fires. First, we need to create a parser object using $parser = xml_parser_create(). Then, we need to create the handler functions, and assign them to the parser object using xml_set_element_handler($parser, 'startElement', 'endElement'). We also need to set our parser options using xml_parser_set_option($parser, XML_OPTION_CASE_FOLDING, 0). Here is our php code so far:</p> <pre><code> $currentElement = ""; // Begin code to create menu from xml file. $varFileXmlFile = "xml_databases/sitemap.xml"; $xmlFile = fopen ($varFileXmlFile, "r"); $xmlString = fread ($xmlFile, filesize ($varFileXmlFile) ); $strMenu = ""; $currentElement = ""; $name = "1"; $link = "2"; $title = "3"; function startElement ($parserHandle, $elementName, $attributes) { // declare the global variables here } // function to handle the end of an element function endElement ($parserHandle, $elementName) { //declare global
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